As is well known, two types of material are suitable for use in making intraocular implants:
either rigid materials such as polymethyl methacrylate (PMMA);
or so-called “flexible” materials such as hydrophilic or hydrophobic acrylic materials, with an example thereof being known under the trademark Hydrogel.
The present invention relates to an implant made with the second type of material.
It is also known that intraocular implants are essentially constituted by two portions comprising firstly an optical portion constituting the system of the implant for correcting vision, and secondly a haptic portion that serves to hold the optical portion centered within the eye, and in the particular example described, within the capsular bag of the eye after the natural lens has been removed.
The haptic portion of the intraocular implant may have various shapes, and the main types of haptic are C-shaped or J-shaped loops, or indeed a circular shape that is connected to the optical portion by arms. The intraocular implant of the invention relates to a haptic portion that is of circular shape.
Once the intraocular implant has been placed in the eye, it must naturally perform the desired optical correction for the patient. This correction depends not only on the characteristics of the optical portion, but also on the position of the intraocular implant within the eye.
It is therefore important for the implant to retain the position within the eye that is initially established by the surgeon. Unfortunately, it is found that after an implant has been put into place in the capsular bag, the capsular bag tends to shrink in diameter over the period subsequent to putting the implant into place. This reduction in diameter may be by as much as 10%.
It will be understood that while the diameter of the capsular bag is reducing, when implants of conventional type are being used, there is a danger that the stresses applied by the capsular bag on the haptic portion as a result of its diameter shrinking will cause the optical portion to move axially along the direction of the optical axis of the eye. In addition, this reduction in diameter can give rise to stresses that lead to deformation of the haptic portion so that it is no longer circularly symmetrical, and that can cause the optical axis of the intraocular implant to be tilted relative to the optical axis of the patient's eye. Naturally, these two risks can give rise to very significant discomfort for the patient who has received the intraocular implant.